养分异质条件下结缕草克隆分株生长及光合作用的生理整合

通过对连接和断开的分株进行不同养分处理,研究养分异质条件下结缕草克隆分株生长及光合作用的变化.结果表明:在养分异质条件下,处于中、高养分水平的母株可以提高与其相连子株的叶长、叶宽、根质量、叶质量、光合速率、气孔导度、蒸腾速率和水分利用效率,高养分条件下分别提高16.0%、8.3%、24.4%、58.1%、30.3%、54.0%、9.2%和21.9%,降低根冠比和胞间CO2浓度,在高养分下分别降低21.6%和31.5%;处于中、高养分水平的子株对与其相连母株的生长及光合特性没有显著影响.在养分异质条件下,结缕草母株对子株存在生理整合,养分梯度越大,整合强度越强.结缕草克隆子株可以从母株获益,但母株不能从子株获益,子株是生理整合单向获益者.     

干旱-高钙对麻栎幼苗非结构性碳水化合物含量和分配的影响

土壤高钙胁迫是干旱-半干旱区影响树木生长的重要环境因子,为阐明干旱-高钙对树木非结构性碳水化合物(Non-structural carbohydrate,NSC)的含量和分配的影响,以麻栎幼苗为研究对象,阐明干旱和干旱-高钙条件对其生长、光合特征及非结构碳水化合物含量与分配的影响。结果表明:干旱显著降低麻栎幼苗生物量,而干旱-高钙处理较干旱进一步降低了麻栎生物量;干旱-高钙在处理初期就能显著抑制麻栎幼苗净光合速率,处理3个月后干旱和干旱-高钙处理的麻栎幼苗光合速率均显著低于对照;干旱处理麻栎幼苗平均非结构性碳水化合物含量增加19.90%,干旱-高钙处理麻栎幼苗整株的平均NSC含量则显著降低25.62%;干旱和干旱-高钙对麻栎幼苗NSC在不同器官间分配也产生不同影响,干旱条件下麻栎幼苗茎中NSC含量增加最多,较对照增加了52.34%,且淀粉的增高幅度(61.94%)高于可溶性糖(25.53%),干旱、高钙共同作用下麻栎幼苗全株平均NSC含量显著减少的同时,NSC积累在叶中,叶NSC含量显著提高32.31%,根、茎中NSC含量则分别显著降低了49.38%和35.31%。干旱-高钙胁迫降低麻栎幼苗NSC含量,且会减少NSC向枝干和根系分配。     

大穗结缕草幼苗耐盐生理机制及耐盐能力研究

以大穗结缕草为实验材料,采用不同质量分数的NaCl处理后,观察盐胁迫对其生长及生理生化指标的影响.结果表明:随着盐胁迫浓度增大,大穗结缕草幼苗株高、鲜重、干重都逐渐下降,而根容量和根冠比却逐渐上升;随盐胁迫浓度的增大,大穗结缕草幼苗叶片细胞质膜透性和MDA含量逐渐增加,脯氨酸含量持续升高;其多数生长和生理指标在≥2.0% NaCl盐胁迫浓度下与对照差异显著,且此时的脯氨酸含量是对照的10倍以上.研究发现,大穗结缕草幼苗地上部分对盐胁迫更敏感、受害更严重;通过体内脯氨酸积累来减轻渗透胁迫是其可能的耐盐生理机制;2.0%盐胁迫可能是大穗结缕草的最高耐盐浓度.     

光资源强度变化对结缕草植株克隆生长特征的影响

克隆植株的生长特征及其表型可塑性反映了其对环境条件变化的适应性。论文以结缕(Zoysia japonica)为研究对象, 采用 4 种均质光照水平(全光照、 30%、 50%和 70%遮荫比例 )和 9 种异质光照格局对结缕草进行处理, 旨在揭示不同光照对结缕草不同发育时期克隆生长特征和表型可塑性的影响。 结果表明 , (1)70%均质全光照(即均匀遮光 30%)条件下结缕草克隆植株生长情况最好, 其总生物量和分株数目等指标都达到最大值。其次为全光照、 50%和 30%均质全光照。 (2)对结缕草克隆植株实施异质光照处理时, 30%遮荫条带对克隆植株生长和克隆构型指标未产生显著影响 ;50%遮荫条带处于植株基部相比处于中、 尾部时, 植株根冠比高, B 分株数目低 , 但对其它指标影响不显著; 70%遮荫条带处于植株基部相比处于中、尾部时, 植株根冠比高, 并且其它指标都显著降低 ; 不同强度的遮荫条带处于植株中、尾部时, 各项指标无显著差异。这一研究有助于了解结缕草克隆植株在不同光照条件下的生长发育特征和适应策略,对于结缕草地的科学经营具有理论和实践指导意义。     

川西云杉幼苗非结构性碳水化合物对土壤温度和水分变化的响应

选取5年生川西云杉（Picea balfouriana）幼苗作为试验材料，于生长季模拟土壤温度和水分变化，研究不同土壤温度和水分处理对幼苗各器官生物量和非结构性碳水化合物（NSC）浓度的影响，以期加深对高海拔树木碳水化合物生理的理解，并为全球气候变化下植物的生理生态响应和动态变迁研究提供基础数据。于人工气候室内采用嵌套设计，设置5个土壤温度梯度（2、7、12、17、22℃），每个温度处理下3个土壤水分处理（干旱处理、正常水分含量处理、饱和水分含量处理）。每9株幼苗为同一个处理，共135株幼苗。试验处理4个月后，测定幼苗各器官生物量、可溶性糖、淀粉和NSC浓度。土壤温度对幼苗总生物量无显著影响，但土壤低温显著降低了根生物量和根冠比；干旱和饱和水分胁迫在较高的土壤温度处理下显著降低了根生物量和根冠比。随着土壤温度降低，各器官可溶性糖、淀粉和NSC浓度并未降低，反而呈现出升高或不变的趋势。。在土壤低温处理下（2和7℃）干旱显著降低了当年生叶的淀粉和NSC浓度以及当年生枝的淀粉浓度；在2和7℃时，干旱和饱和水分胁迫显著降低了根中淀粉和NSC浓度。土壤低温和水分胁迫对幼苗地上地下生物量分配影响显著，分配给光合器官的生物量相对增多。土壤低温并没有导致碳受限，甚至各器官NSC浓度随着土壤温度降低有升高的趋势，因此，土壤低温下非结构性碳水化合物的不足不是限制川西云杉幼苗存活和生长的原因，从侧面支持了林线形成的"生长抑制"假说。此外，干旱胁迫在土壤低温下很可能会导致川西云杉的"碳饥饿"。     

克隆整合是否有助于空心莲子草抵抗菟丝子的短期寄生?

关于克隆植物通过克隆整合抵御逆境能力影响的研究已有很多,但克隆整合是否能抵御植物寄生的研究还比较缺乏。本文利用匍匐茎克隆植物空心莲子草和1年生寄生植物菟丝子作为研究系统,检验假说"克隆整合有助于克隆植物抵抗寄生植物的寄生胁迫"。在实验中,相连分株分别经历了以下处理:M+-D-(分株对中母株被寄生,子株不被寄生),M--D+(母株不被寄生,子株被寄生),M+-D+(母株、子株均被寄生),M--D-(母株、子株均不被寄生)。研究发现,菟丝子寄生显著影响了空心莲子草的叶绿素相对含量、最大光量子产量等生理指标,以及叶片数、匍匐茎长度、分株数等生长指标,但不同处理间的生物量没有显著差异。本实验的结果没有支持实验假说。这样的结果可能是由于本实验时间较短所引起的,表明克隆整合适应性的表达不是无条件的。进一步实验应该既能够检验短期效应也能够检验长期效应。     

模拟增温和功能群去除对岷江冷杉幼苗存活和生长的影响

通过模拟增温和功能群去除试验,研究不同功能群的草本植物在岷江冷杉幼苗更新定植过程的作用,分析其在温度升高条件下生理指标的变化.结果表明:增温提高了岷江冷杉幼苗的存活率和植物体内非结构性碳水化合物含量,但抑制了幼苗的生长和根冠比.岷江冷杉幼苗的非结构性碳水化合物含量,尤其是可溶性糖含量与存活率呈显著正相关.不增温处理中,草本植物降低了幼苗的存活率,促进幼苗的株高生长和地上生物量积累,禾本科植物和杂类草抑制了幼苗根系生长和地下生物量的积累;增温处理中,杂类草的存在提高了幼苗的存活率,莎草科则显著抑制了幼苗根系生长和地下生物量的积累,禾本科植物和杂类草抑制了幼苗的高生长和地上生物量积累.模拟增温提高了林线树种岷江冷杉幼苗的存活率,但使其面临来自草本植物更剧烈的竞争,抑制其生长.     

氮添加对油松幼苗不同径级细根碳水化合物含量的影响

氮(N)沉降正在对全球森林生态系统产生显著影响。目前关于氮沉降如何通过影响树木不同径级细根碳水化合物含量,进而影响树木生理特征及生长的机制尚不清楚。本文以2年生油松(Pinus tabuliformis)幼苗细根为对象,研究了短期(2年)氮添加(0、3、6、9g N·m~(-2)·a~(-1),分别记为N0、N3、N6、N9)对不同径级(0~0.5、0.5~1和1~2 mm)细根中非结构性碳水化合物(NSC)和结构性碳水化合物(SC)含量的影响。结果表明:(1)0~0.5 mm细根中碳水化合物含量(512.97 mg·g~(-1))显著低于1~2 mm细根中碳水化合物含量(638.83 mg·g-1)。0~0.5 mm细根中NSC、可溶性糖和淀粉含量显著低于0.5~1及1~2mm;(2)随着细根径级的增加,SC含量和纤维素含量呈增加趋势,而木质素含量呈降低趋势。N添加对3个径级细根中不同碳水化合物组分的影响不同。N添加对0~0.5和0.5~1mm细根中NSC、可溶性糖和淀粉含量均无显著影响,但N9处理显著降低了1~2 mm细根中NSC和可溶性糖含量(16.20%和29.90%),对淀粉含量无显著影响。此外,N3处理显著增加了0~0.5 mm细根中可溶性糖含量(69.65%);(3)N添加对细根中SC、木质素含量没有显著影响,但N3处理显著增加了最细两级根(0~0.5和0.5~1 mm)纤维素含量(35.3%和57.0%),N9处理显著降低了1~2 mm细根中纤维素含量(30.39%);(4)N3处理显著增加了0~0.5 mm细根中NSC/SC,而对另两级根系中该比率无显著影响。结果表明,N添加可能通过影响最细两级根(0~0.5和0.5~1 mm)中NSC、可溶性糖含量及NSC/SC影响植物细根的生理功能和生长。     

不同养分水平对飞机草生长与生物量分配的影响

采用温室盆栽模拟实验研究了不同养分水平对外来入侵植物飞机草(Chromolaena odorata)的生长性状、生物量积累以及生物量分配格局的影响。实验共设置5 种养分浓度处理, 分别为Hoagland 标准营养液的10%、25%、50%、100%和200%溶液。结果表明: 养分水平对飞机草植株的生长性状以及生物量的积累、分配产生显著影响。随着养分水平的增加, 飞机草的总分枝数量、长度以及一级分枝数量、长度持续增加, 并且100%、200%处理还能促进二级分枝的萌发生长。飞机草的叶片数、总叶面积、总生物量以及茎、叶两器官生物量随养分水平的上升显著增加, 但株高、根生物量不受养分浓度变化的影响。根生物量比、根冠比随养分水平的提高显著下降, 叶生物量比则显著上升, 但茎生物量比在各养分浓度保持稳定。叶面积比、叶根比、RGR 亦随养分含量的上升显著增加。说明养分资源丰富的环境将促进飞机草的地上部生长, 而生物量分配格局的变化可能是其在入侵蔓延过程中适应养分异质性生境的重要生态策略。     

克隆整合对异质性土壤养分生境下薇甘菊生长的影响

环境资源的异质性在自然界中普遍存在。克隆植物能通过克隆整合较好地适应异质性生境。本文以海南外来强入侵性植物薇甘菊为材料,通过温室盆栽试验,研究克隆整合对异质性土壤养分生境下薇甘菊克隆片段生长的影响。结果表明:在养分异质下,克隆整合显著提高了低养分斑块分株的生物量,但同时降低了高养分斑块分株的生物量,对克隆片段总体的生长无显著影响,且这一结果不受资源输送方向的影响。克隆整合对薇甘菊克隆分株的光合速率和比叶面积影响较小,但当近端分株处于高养分条件时,其改变了克隆分株的根冠比。这些结果指示:克隆整合有利于异质性土壤养分条件下薇甘菊对低养分斑块的占领。因此,克隆整合可影响薇甘菊对资源异质性生境的入侵能力,它使薇甘菊能够扩展到低养分斑块,从而提高其入侵扩散能力。     

The effects of physiological integration on biomass partitioning in plant modules: an experimental study with the stoloniferous herb Glechoma hederacea

Morphological and physiological plasticity are crucial attributes enabling plants to acquire resources from heterogeneous habitats. Although physiological integration can modify biomass partitioning in modules, especially when connected modules experience different conditions, its ecological importance has been largely overlooked. This experiment examined its effects on above- and belowground biomass partitioning by modules in the stoloniferous herb Glechoma hederacea. We studied how biomass allocation to roots by younger ramets was affected by connection to older ramets, and by nutrient conditions. A lower proportion of biomass was allocated to roots by younger ramets growing under low nutrient (LN) conditions when connected to older ramets in high nutrient (HN) conditions than when they were isolated, demonstrating localised modification of biomass partitioning due to physiological integration. The proportion of biomass allocated to roots by younger ramets was also lower when connected to older ramets in HN conditions than when connected to older ramets in LN conditions. Thus, the effect of integration on biomass partitioning depended on the nutrient conditions experienced by connected ramets. Such changes in biomass partitioning would result in more extensive stolon growth, and greater lateral displacement of new ramets. Understanding the ecological implications of phenotypic plasticity in plants will require further examination of the effects of physiological integration when connected modules experience contrasting growing conditions. This study demonstrates that such integration affects the biomass allocation strategy of connected ramets, enhancing resource acquisition in heterogeneous habitats. The widespread success of clonality in many communities is likely to be strongly promoted by this characteristic.     

Soil nutrient patchiness affects nutrient use efficiency,though not photosynthesis and growth of parental Glechoma longituba ramets: both patch contrast and direction matter

Aims Most plants are clonal in nature. Clonal ramets can share water, nutrients and photosynthate, especially when they experience patchy resources. Patch contrast (i.e. a difference in resources among patches) and patch direction (i.e. source–sink relations) are among the basic attributes of spatial patchiness. Here, I hypothesize that young established ramets in nutrient-rich patches support old ramets in nutrient-poor patches when ramets are subjected to different patch contrasts and patch directions.Methods In a greenhouse experiment, old and young ramets of Glechoma longituba were grown in four combinations consisting of patch contrast and patch direction. Minus patch direction refers to a patch combination in which parent ramets grow in nutrient-rich patches while connected daughter ramets grow in nutrient-poor ones and plus patch direction is the opposite direction. I measured photosynthesis and fluorescence traits, harvested all ramets, took morphological measures, weighed their dry mass and determined their nutrient uptake and use.Important findings For parental ramets of G. longituba, patch contrast and patch direction and their interactions had no significant effects on net photosynthetic rate, maximal fluorescence yield, photochemical quenching (quenching refers to any process which decreases the fluorescence intensity of a given substance), non-photochemical quenching, nutrient uptake, biomass and stolon weight ratio. Patch direction alone significantly affected root weight ratio. Large patch contrast enhanced N use efficiency (NUE) and P use efficiency (PUE); plus patch direction decreased NUE, but increased PUE; the patch contrast by patch direction interaction affected PUE and K use efficiency (KUE). There were significant interactions between patch direction and patch contrast on PUE and KUE. It is concluded that soil nutrient patchiness may influence nutrient use strategies, but not nutrient uptake, photosynthesis and growth of parent ramets of G. longituba connected to daughter ramets, and that patch contrast and patch direction jointly affect PUE and KUE.     

The effects of clonal integration on morphological plasticity and placement of daughter ramets in black locust (Robinia pseudoacacia)

We studied the field response of Robinia pseudoacacia L. to light, total soil nitrogen, available soil phosphorus and soil pH. Results indicated that there was very strong clonal integration between mother and daughter ramets. Mother ramets can provide nitrogen and phosphorus to daughter ramets sufficient for their continued growth through strong clonal integration, but cannot provide enough photosynthate. With clonal integration, soil nitrogen and phosphorus availability had no effect on biomass allocation to roots, number of ramets and length of connection roots. Biomass allocation to roots increased markedly and responded to nitrogen and phosphorus availability, when the connections were severed. Light had a significant effect on the percent of biomass allocation to leaves and number of ramets, but no effect on the length of connection roots. Daughter ramets allocated more resources to leaves, and clones placed more daughter ramets in high light patches than in low light patches. Soil pH had a significant effect on ramet number and connection root length. Clones concentrated in alkaline patches and escaped from acid patches through selective placement of daughter ramets and changing the length of connection roots. We suggest that the clonal integration may be very strong and provide sufficient soil resources to daughter ramets, then affect the daughter ramets’ morphology and placement, if the size of a specific ramet is significantly larger than the other ramets in an arbor clone.     

Physiological integration impacts nutrient use and stoichiometry in three clonal plants under heterogeneous habitats

Physiological integration facilitates clonal plants to deal with heterogeneous resources. However, little is known about how nutrient patchiness affects its use and stoichiometry in clonal plants. We conducted an experiment with Cynodon dactylon, Glechoma longituba, and Potentilla reptans to address the effects of physiological integration on nutrient use efficiency and N:P ratios. For C. dactylon, the effects of nutrient patchiness on N use efficiency (NUE), P use efficiency (PUE), and N:P ratio were stronger in daughter ramets than in parent ramets; for G. longituba, nutrient patchiness affected PUE and N:P ratio of parent and daughter ramets, but not NUE; for P. reptans, nutrient patchiness decreased NUE, PUE, and N:P ratio, regardless of parent or daughter ramets. PUE was associated with N:P ratios in three clonal plants and this association of NUE with N:P ratios varied with species. Our findings suggest that physiological integration alters nutrient use efficiency and N:P ratios of clonal plants under patchy nutrients and that these effects are linked to clonal species identity.     

The invasive plant Alternanthera philoxeroides benefits from clonal integration in response to defoliation

Many notorious alien invasive plants have the capacity for vigorous clonal growth, and clonal integration may contribute to their invasiveness in response to various disturbances. Here, it is hypothesized that clonal integration affects the growth, biomass allocation, physiology, and compensatory response of the alien invasive clonal plant Alternanthera philoxeroides when faced with defoliation. To test these hypotheses, a growth experiment was conducted to investigate the effect of clonal integration on the responses of A. philoxeroides to different levels of defoliation. Daughter ramets that had been grown with stolon connections that were either severed from or connected to the mother plant were subjected to four defoliation levels: 0 (control), 30% (mild), 60% (moderate) and 90% (heavy) removal of leaf tissue. Defoliation greatly decreased growth (total biomass, number of ramets and total stolon length) but increased the maximum quantum yield of photosystem II (F_v/F_m) of daughter ramets. Clonal integration significantly increased growth, F_v/F_m and contents of non-structural carbohydrates (soluble sugars and total non-structural carbohydrates) of A. philoxeroides, and these effects were larger under heavier defoliation. Moreover, clonal integration markedly reduced the shoot/root ratio of A. philoxeroides, and these effects tended to increase with increasing levels of defoliation. These results support our hypothesis that A. philoxeroides benefits from clonal integration in response to defoliation, suggesting that clonal integration may be closely related to the invasiveness of A. philoxeroides in natural habitats with frequent disturbances.     

Clonal integration in Ranunculus reptans: by‐product or adaptation?

We studied fitness consequences of clonal integration in 27 genotypes of the stoloniferous herb Ranunculus reptans in a spatially heterogeneous light environment. We grew 216 pairs of connected ramets (eight per genotype) with mother ramets in light and daughter ramets in shade. In half of the pairs we severed the stolon connection between the two ramets at the beginning of the experiment. During the experiment, 52.7% of the ramet pairs with originally intact connection physically disintegrated. We detected significant variation among genotypes in this regard. Survival of planted ramets was 13.3% higher for originally connected pairs. Moreover, there was significant variation among genotypes in survival, in the difference in survival between plant parts developing from mother and daughter ramets, and in the effect of integration on this difference. In surviving plants connection between ramets decreased size differences between mother and daughter parts. Variation among genotypes was significant in growth and reproduction and marginally significant in the effect of physiological integration on growth and reproduction. Connected daughter ramets had longer leaves and internodes than daughters in severed pairs indicating that integration stimulated plant foraging in both the vertical and the horizontal plane. Observed effects of integration on fitness components in combination with genetic variation in maintenance and effects of connection indicate that clonal integration in R. reptans has the capability to evolve, and therefore suggest that clonal integration is adaptive. If genetic variation in integration is common, future studies on clonal integration should always use defined genetic material and many clones to allow extrapolation of results to population and wider levels.     

Response of physiological integration in Trifolium repens to heterogeneity of UV-B radiation

Physiological integration has been documented in many clonal plants growing under resource heterogeneity. Little is still known about the response of physiological integration to heterogeneous ultraviolet-B radiation. In this paper, the changes in intensity of physiological integration and of physiological parameters under homogeneous and heterogeneous ultraviolet-B radiation (280-315 nm) were measured in order to test the hypothesis that in addition to resource integration a defensive integration in Trifolium repens might exist as well. For this purpose, homogeneous and heterogeneous ultraviolet-B radiation was applied to pairs of connected and severed ramets of the stoloniferous herb Trifolium repens. Changes in intensity of water and nutrient integration were followed with acid fuchsin dye and ¹⁵N-isotope labeling of the xylem water transport. In order to assess the patterns of physiological integration contents of chlorophyll, ultraviolet-B absorbing compounds, soluble sugar and protein were determined and activities of superoxide dismutase (SOD) and peroxidase (POD) measured. When ramets were connected and exposed to heterogeneous UV-B radiation, the velocity of water transportation from the UV-B treated ramet to its connected sister ramet was markedly lower and the percentage of ¹⁵N left in labelled ramets that suffered from enhanced UV-B radiation was higher and their transfer to unlabelled ramets lower. In comparison with clones under homogeneous ultraviolet-B radiation, the content of chlorophyll, ultraviolet-B absorbing compounds, soluble sugar and activities of SOD and POD increased notably if ultraviolet-B stressed ramets were connected to untreated ramets. Chlorophyll and UV-B absorbing compounds were shared between connected ramets under heterogeneous UV-B radiation. This indicated that physiological connection improved the performance of whole clonal plants under heterogeneous ultraviolet-B radiation. The intensity of physiological integration of T. repens for resources decreased under heterogeneous ultraviolet-B radiation in favor of the stressed ramets. Ultraviolet-B stressed ramets benefited from unstressed ramets by physiological integration, supporting the hypothesis that clonal plants are able to optimize the efficiency of their resistance maintaining their presence also in less favorable sites. The results could be helpful for further understanding of the function of heterogeneous UV-B radiation on growth regulation and microevolution in clonal plants.     

Clonal integration enhances flood tolerance of Spartina alterniflora daughter ramets

Recently, considerable attention has been paid to the invasion of the clonal plant Spartina alterniflora into coastal wetlands at lower elevations. In this experiment, we tested whether clonal integration improved flood tolerance in S. alterniflora daughter ramets. Daughter ramets at two growth stages (young and old ramets) were flooded to water levels of 0, 9 and 18 cm above the soil surface, and the rhizomes between mother and daughter ramets were either severed or left intact. Biomasses of connected ramets grown in controls or in shallow and deep water treatments were 119%, 108% and 149% higher in the old ramet group than those of severed ramets, respectively, whereas they were 3.0, 3.3 and 11.2 times higher in the young ramet group, respectively. At the end of the experimental period, the shoot height, connected with young ramets, in shallow and deep water treatments increased by 19% and 26%, respectively, over that in the control treatments, whereas the old ramets increased by 11% and 39%, respectively. In contrast, the shoot height of the severed young ramets was 27% and 26% lower in shallow and deep water treatments than in the control treatment, respectively. However, the shoot height of the severed old ramets remained constant with increasing water depth. We conclude that clonal integration enhances the flood tolerance of S. alterniflora daughter ramets, and the trait of clonal integration plays more important roles in severe flooding stress conditions and at early growth stages.     

毛乌素沙地游击型克隆半灌木羊柴对局部沙埋的反应

不同程度的沙埋是生长在干旱和半干旱区内陆沙丘的植物经常遭遇的事件,沙埋可以改变植物所处的生物和非生物环境条件。已有研究表明不同程度的沙埋对于植物的影响不同。轻微程度的沙埋可以增加植物高度、促进生物量的积累和新生分株的产生。如果沙埋强度不断增加,对植物的影响由正效应逐渐转变为负效应。即超过一定沙埋阈值后,沙埋会削弱植物的生长,甚至影响植物的存活。干旱和半干旱区内陆沙丘中常常生长着许多克隆植物,克隆整合常常可以缓解克隆植物分株所遭受的局部环境胁迫。根茎型克隆植物羊柴(Hedysarum laeve)是毛乌素沙地的优势半灌木之一,也是当地重要的固沙植物。为了探讨克隆整合的作用是否可以提高沙埋阈值,并有助于羊柴忍受高强度的沙埋,以其为研究对象开展了野外实验。结果表明:轻微程度的沙埋(例如沙埋深度是原始羊柴分株高的10%~20%)可以加速羊柴分株的高生长,提高叶片生物量、茎生物量以及整个地上部分的生物量。高强度的沙埋(例如沙埋深度是原始羊柴分株高的80%~100%)会削弱羊柴分株的存活和生长。在与不遭受沙埋分株相连的情况下,羊柴分株遭受沙埋的阈值高于没有分株相连的,而且在高强度的沙埋下,前者(有分株相连的遭受沙埋的分株)比后者(没有分株相连的遭受沙埋的分株)在株高增量、茎生物量、叶片生物量以及地上分株生物量上都要显著高。这暗示着克隆整合提高了羊柴遭受沙埋的阈值并有助于羊柴分株忍受高强度的沙埋。